Implantable diagnostic apparatuses have already been described, for example, as parts of implantable insulin pumps. Such apparatuses essentially comprise an implantable measurement chamber in which a biosensor generates an analyte-dependent signal which, for its part, serves to control the insulin pump. These apparatuses have to be exchanged periodically when the insulin reserve is exhausted. Since this exchange takes place relatively frequently, the exchange interval is frequently shorter than the service life of the biosensors.
What is disadvantageous in the case of previous methods, and probably also a reason why the previous methods for glucose determination in connection with insulin pumps have not been applied to other parameters, is the problem that would arise if the biosensors are in contact with blood over a relatively long period of time and then their function is impaired, or even rendered impossible, by deposits such as, for example, fat- or protein-containing deposits (clots).
In particular, methods for determining coagulation parameters, which, by their nature, are often associated with clot formation, are not considered to be promising.
The object underlying the present invention is to provide an implantable diagnostic apparatus which enables the intervals between the exchanges of the apparatuses to be significantly lengthened and which allows the detection of coagulation and fibrinolysis parameters to determine hemostasis disturbances, e.g. by detecting factor VIII or measuring the PT (prothrombin) time.
It has been found, surprisingly, that the apparatus according to the invention, either as an individual measurement chamber or as an apparatus containing a plurality of measurement chambers, can advantageously be used to determine hemostasis disturbances, i.e. any malfunction of the hemostasis system.